


lend me your strength

by doxian



Series: Sports Winter Anime Games (SWAG) 2016 [1]
Category: Haikyuu!!
Genre: Alternate Universe - Urban Fantasy, Anal Sex, Blood, Demons, Established Relationship, M/M, Plot What Plot/Porn Without Plot, Sex Magic, Sports Winter Anime Games 2016, Temperature Play
Language: English
Status: Completed
Published: 2016-01-13
Updated: 2016-01-13
Packaged: 2018-05-13 19:15:19
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,891
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5713984
Author URL: https://archiveofourown.org/users/doxian/pseuds/doxian
Summary: <blockquote class="userstuff">
              <p>To Ushijima, it's all just a matter of practicality: why go out of your way to hunt for prey when there's an easy energy source readily available?</p>
            </blockquote>





	lend me your strength

**Author's Note:**

> [written for this SWAG prompt](https://referees.dreamwidth.org/3776.html?thread=340928#cmt340928): "FHQ AU. Shirabu is an incubus, and Ushijima sometimes supplies him with energy from sex. When Shirabu is really tired and weak, Ushijima offers to ride him so Shirabu doesn't have to waste energy fucking him. Since Shirabu is an incubus, do what you want with involving magic in sex or writing Shirabu with a demon dick (optional: detail about that up Ushijima's ass)."
> 
> took some liberty with the prompt by going urban fantasy instead of FHQ and not-quite-an-incubus for Shirabu.

It's late by the time Ushijima makes it to Shirabu's apartment. He'd received his text at around lunchtime, but he hadn't been able to make his way over until several hours after his workday had ended. It had been frenetically busy at the office, this week, and his boss had requested that he stay to help, so of course he hadn't left until he was sure everything had been taken care of. 

He wishes he could have just been upfront about the situation. "If you'll excuse me, I have to go home early and fuck my boyfriend so he can feed off of my energy. He's a demon, you see." But he'd tried that last time, and it hadn't gone over well. He knows better than to try it again. He forgets that some people aren't terribly accepting of the idea of a human dating a magical being. 

He hadn't stopped thinking about Shirabu the entire time he'd been working - eager to finish so that he could leave and see to what was needed sooner rather than later. His impatience had worked against him, though, causing him to make silly mistakes that only made his job take even longer. 

So when Ushijima boards his train, the evening darkness obfuscates how the view shifts from the grit and glitz of the city center to the homelier, more modest buildings of the outskirts. 

The street leading to Shirabu's building is deserted at this hour. The light from the street lamps is eerie and faint, reflecting in the puddles the day's rain has left behind, turning the pavement to lacquer. The wetness makes the uneven cobblestones even more slippery and treacherous than usual, but Ushijima walks at a brisk pace, sending rainwater splashing up around his ankles with every step. Once he arrives at the right building he takes the stairs two at a time. He lets himself into Shirabu's apartment without knocking. 

The first thing he notices when he gets indoors is that it's oppressively hot, especially compared to the damp springtime chill outside. 

"Wakatoshi?" Shirabu calls from down the hall. 

Ah. His voice sounds different. Gravelly. Like fistfuls of brimstone grinding together; like flames spitting from a over-stoked campfire. 

Ushijima can guess at what had happened.

"Kenjirou?" He follows Shirabu's voice to the bedroom, shrugging off his suit jacket. Sweat is already seeping through his shirt. 

Shirabu is laying listlessly on his bed, wearing nothing but a pair of sweatpants. Ushijima pauses in the doorway so he can drink in the sight of him. Shirabu's skin has turned rough, leathery, and black as pitch. Each of his fingers and toes is tipped by a sharp, curved claw, and he's sporting a pair of ram's horns that Ushijima had always found quite stately and dignified. 

"Don't go into the bathroom," Shirabu says, coughing, sending bright orange sparks flying from his mouth. "I accidentally set fire to the shower curtain earlier. It's not pretty in there right now." 

Ushijima was right. Shirabu is so tired and hungry that he's dropped his glamour completely. 

"You should have told me it was this bad," Ushijima reprimands him. He's hung up his coat and tie and is already unbuttoning and removing his shirt, draping it neatly over the back of Shirabu's desk chair. 

"I didn't want to take you away from work," Shirabu says, petulant. "You know I don't like asking you to do this if I can help it to begin with."

"It's fine," Ushijima says, curt and matter of fact.

Shirabu just clicks his tongue, so Ushijima doesn't pursue the subject further - for now. Shirabu prefers to feed on strangers, insisting that it's somehow dishonourable towards Ushijima for him to feed while the two of them have sex. And yet once they'd started dating, Shirabu had stopped using sex with other people as a source of energy. Since killing and injuring people is out of the question - demon or not, he's still subject to the law - he'd been confined to voluntary bloodletting, and Ushijima knows that's the most feeble and unsatisfying way to feed.

It all seems so terribly inefficient. To Ushijima, it's all just a matter of practicality: why go out of your way to hunt for prey willing to bleed for you when there's an easy energy source readily available? Ushijima can often talk Shirabu around to his point of view - where Shirabu might be stubborn, Ushijima is determined - but on this matter, Shirabu absolutely refuses to budge. 

It's a shame, really. Shirabu is attractive enough in his way in his human form, but like _this_ he's irresistible. 

Ushijima unbuckles his belt and steps out of his pants and boxers at once. He does not take off his socks. 

Shirabu watches him hungrily as he approaches the bed. Shirabu still looks like himself, even though he's coal-black and his eyes glow like embers without a trace of a human pupil or iris. His form is the same - slim and wiry. The look on his face isn't dissimilar to how he looks when they have sex normally, either - just more unrestrained, more abandoned. It's one of the many things Ushijima likes about sex with Shirabu like this.

"You look famished," Ushijima says, holding Shirabu's gaze and kneeling on the mattress. "You can barely even lift your head." 

"So help me, then," Shirabu says, his voice a deep purr. His eyes rove over Ushijima's naked form, now that he's closer, from his shoulders to his abs to his cock and back up again. 

Ushijima says nothing. He just reaches for Shirabu's already tenting sweatpants. The fabric snags when Ushijima pulls them down, and after Shirabu kicks the garment off Ushijima runs his hands up his boyfriend's legs, feeling the heat under his fingers. Shirabu is so _warm_ , like there's a furnace alight under his skin. 

He works over Shirabu's thighs until he reaches his cock. It's as dusky black as the rest of him, tapering off to a blunt point with ridges running along the underside and hard bumps dotting either side, graduating from larger to smaller towards the tip. _Beautiful_. Ushijima wraps his hand around it, his finger and thumb barely meeting, and puts out his tongue to lick along each pronounced ridge. It's even warmer than the rest of Shirabu, and with less give - more like heated metal than flesh.

But using his mouth isn't going to be enough. Not for this.

" _Wakatoshi_ ," Shirabu growls, the noise rumbling from deep in his belly and creeping up Ushijima's spine.

Ushijima straightens and straddles Shirabu's hips. He holds out a hand, and Shirabu rummages in his bedside for lube without Ushijima having to ask. A loud _crack_ rends the air when Shirabu's claw scrapes against the wooden drawer as he pushes it shut.

Ushijima makes quick work of prepping himself, pushing two fingers in straight off the bat. He isn't as thorough as he should be, but he and Shirabu are both too eager. He coats Shirabu's cock in lube before guiding it towards his hole, abandoning the lube bottle somewhere in the bedsheets. 

Shirabu is breathing heavily, his claws doing a number on the white bedsheets as he curls and uncurls his fingers. 

Ushijima wants to take in Shirabu all at once. Hurting himself would mean stopping, though, so he instead sinks down, slowly, letting out a low groan at the texture rippling inside him.

Shirabu is still watching him with an all-consuming intensity, even though he's still too tired to move, his narrow, forked tongue slipping out of his mouth for a moment along with a lick of flame. (This is the only thing Ushijima dislikes about Shirabu's natural form - they can't kiss, not unless Ushijima wants to get his lips burned off by the miniature inferno contained within Shirabu's mouth and throat. Sometimes he wonders if it'd be worth it.) 

Ushijima has definitely not used enough lube. That much is evident as soon as Shirabu bottoms out. The stretch of Shirabu inside him _burns_ , and he has to take a moment to breathe. But the burn isn't exactly unpleasant, and there's the counterpoint of how Shirabu is pressing right up against Ushijima's prostate without even trying due to sheer girth alone. 

When Ushijima finally starts moving, Shirabu lets out a long sigh of relief. 

Ushijima hasn't stopped sweating since he entered the apartment. It's even worse, now, droplets gathering at his temples and trickling down his face. Shirabu's skin burns against his like a brand where their legs touch, and Ushijima has adjusted to the stretch only to notice that Shirabu's dick feels almost _scalding_ inside of him. 

He continues riding Shirabu at a steady pace, even with how distracted he is, even though he can barely focus on anything aside from the lustful heat of Shirabu's gaze and the point where they're joined. Usually Ushijima can fuck Shirabu for hours, like a piston, but now he can only keep up the powerful motions of his hips for a few minutes before his energy starts to fade and he's limited to grinding on Shirabu's dick in shallow circles. 

Not fading, though. His energy isn't fading - Shirabu is leeching it away. Shirabu's eyes are burning bright, now, and a predatory smile is on his face. He grips Ushijima's hips, thrusting up into him hard and fast. Ushijima tries his best to meet Shirabu's thrusts, but his legs are shaking from a combination of weakness and the pure pleasure of Shirabu inside him; Shirabu's dick is all hard, unyielding undulations pressing against places deep inside Ushijima that send starlight singing through his body. 

Shirabu sighs again - a rolling wave of heat - and grips Ushijima's hips harder, pricking at his skin. "Let me," Shirabu pleads, Ushijima grunts his assent, and Shirabu digs his claws in, moves them down to scratch deep welts in the meat of Ushijima's strong thighs, leaving stinging stripes of red in his wake. _Bloodletting,_ Ushijima thinks blissfully. Shirabu can feast on even more of his energy like this.

" _Wakatoshi_ ," Shirabu moans, his voice clearer now, ringing with fresh power and echoing off the walls. Shirabu calls his name like a prayer, an incantation, and Shirabu is relentlessly stretching him open, and when Ushijima comes his orgasm is so overwhelming that he squeezes his eyes shut and falls forward, blacking out. 

When he comes to, Shirabu is spooned up against his back, his glamour back in place. Ushijima's legs seem to be bandaged up. 

"You alright?" Shirabu asks when he feels Ushijima stirring, pressing a gentle kiss to his shoulder. His voice is quiet again, affectionate, nothing left of the ravenous creature from earlier.

"Mmm," Ushijima says. It's all he can manage. He's sore, and _exhausted_ , but it's nothing a bit of sleep can't fix. 

"Thank you," Shirabu says. "That really helped. I feel amazing." 

"I told you. It's no problem," Ushijima says, turning to glance at Shirabu over his shoulder before looking away again. "I don't mind doing that for you." 

Shirabu laughs into his hair. Ushijima can feel the light puffs of breath against his ear.

"Well. I love you for doing it, anyway. ...Hey, I'm going to get up. I've spent enough time being useless today, but you should keep resting."

Shirabu says this, but he doesn't move, cradling Ushijima in his arms until he drifts off to sleep.


End file.
